Panel air filters having a multiple pocket configuration are well known and are commercially available from various sources such as Donaldson Company, Inc., Pall Corp., TriDim Filter Corp., and Koch Filter Corp. An example of a V-pocket panel filter is the product generally known as “Pocket Filter” from Donaldson Company, Inc., having parts nos. P03-0204, P03-0205, P03-0256, and P03-0257. Such pocket filters are three-dimensional panel filters have low pressure drop therethrough. They are termed “pocket filters” due to the multiple pockets formed by the filter media.
It is well established in the filter industry that by increasing the amount of filter media, additional media surface area can be packaged into a given volume, thereby increasing dust collection and lowering face velocity. Pleating is a well known mode for increasing the amount of media; decreasing pleat height and increasing pleat density further increases the amount of media.
Such is the basis for pleated pocket panel filters. An example of such a product is available from Donaldson Company, Inc. under the product designation “Mini-Pleat”. A disadvantage, however, is an increase in pressure drop, across the media, that results from the high dust collection.
A partial section of another known pleated pocket panel filter, having a constant pleat height, is shown in FIG. 1. The typical air flow path through the panel pockets is also shown in FIG. 1. As can be seen, the air path has two generally 90 degree turns, which also increases the pressure drop across the panel.
An attempt to decrease the pressure drop, by maintaining a generally straight air flow path through a panel filter, but not a pocket panel filter, is described in U.S. patent publication No. US 2004-0187689 A1, which corresponds to PCT application WO 04/052504. This reference discloses a filter element having Z-filter media, which is composed of a plurality of media flutes. Such a construction can be cleaned by sending a reverse pulse of air through the Z-filter media. A representative product is available from Donaldson Company, Inc. under the designation “PowerCore XLR Panel Filter”.
Although many products are available and function adequately, there is always room for improvements.